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Re: Belt Grinder Build

Originally Posted by Tarmstrong

Thanks for all the reply’s guys...sorta what I thought about my motor.

Anybody need a good single speed motor?

Can't help you on that single phase motor, but are you in the bay area by chance?

Here's a motor that would be good for a belt grinder, 3HP Maraton 3450RPM 3 phase for $100. (there's 3 motors, see the Marathon)

https://sfbay.craigslist.org/pen/tls...124790782.html

Re: Belt Grinder Build

Thanks for all the reply’s guys...sorta what I thought about my motor.

Anybody need a good single speed motor?

Re: Belt Grinder Build

Originally Posted by jh1990

Single phase output VFDs do exist but I believe a start cap is a no go with them.

I've never heard that, I thought you needed a 3 phase motor to use a VFD. They must be expensive for single phase, I've never seen one I don't think...

You can pick up 3 phase motors cheap on craigslist, for a belt grinder a 2HP or 3HP is good as that's the sweet spot for affordable VFDs.

When I say affordable I mean in the $150-$300 range.

A lot of people use the KB Electronics VFDs for belt grinders as they are enclosed so grinding dust doesn't get to the electronics. You can put a VFD in your own box though to save some $$$s, the KB Electronics VFD a bit more than a normal VFD, but convenient for a belt grinder and why so many people use them for that purpose.

All of our mileage varies.

Re: Belt Grinder Build

Originally Posted by scsmith42

Capt, that is a very well crafted build! It could easily be mistaken for a factory built product. Thanks for sharing.

Scott

Thank you!

Re: Belt Grinder Build

that is a 2 HP motor if you want to increase the belt speed you can increase the drive wheel size, but you still have a single speed belt grinder.

Re: Belt Grinder Build

no sir that is a Capacitor start motor, the 2 humpy things are capacitors. These give a phase shift to single phase motor to help start, (this gives them higher starting torque) when they reach almost normal speed a centrifugal switch removes them from the motor power. The motor continues to run a normal speed at that point. What a VFD does if change the power frequency to change the speed, the motor still gets full voltage, there for still has the power to rotate. This is done with the electronics in the VFD, even with the 60 HZ input the output can vary the Hz output. As I said the one I use can go up to 90 Hz and this is why it can rotate faster than the normal rpm of the motor.

Re: Belt Grinder Build

Originally Posted by Tarmstrong

Since you know way more than me about this...question.

This is the motor I have...can it be run with a VFD device of some sort? I currently have it wired to run 220/240
Attachment 1711605

Thanks for any input...

Single phase output VFDs do exist but I believe a start cap is a no go with them.

I am definitely not an expert but I've always figured it's not worth the effort especially with an abundance of 3 phase motors available.

Just make sure you get one that is TEFC with the same frame you have now.

Sent from my Nexus 6P using Tapatalk

Re: Belt Grinder Build

Originally Posted by acourtjester

I change my motor out to use a single phase input 120 VAC to 3 phase 220 VAC output, this allows for full speed control. the VFD in the image will allow up to 90 hz to the motor for 1.5 times normal speed, some of the more expensive ones will to 120 Hz or 2 times normal speed. You cannot use a speed control on a capacitor start motor, because they have a speed switch the drops the capacitor after it reaches the set speed. Running slower will cause something to smoke, either the motor of speed controller.

Since you know way more than me about this...question.

This is the motor I have...can it be run with a VFD device of some sort? I currently have it wired to run 220/240
Attachment 1711605

Thanks for any input...

Re: Belt Grinder Build

Capt, that is a very well crafted build! It could easily be mistaken for a factory built product. Thanks for sharing.

Scott

Re: Belt Grinder Build

Originally Posted by acourtjester

I change my motor out to use a single phase input 120 VAC to 3 phase 220 VAC output, this allows for full speed control. the VFD in the image will allow up to 90 hz to the motor for 1.5 times normal speed, some of the more expensive ones will to 120 Hz or 2 times normal speed. You cannot use a speed control on a capacitor start motor, because they have a speed switch the drops the capacitor after it reaches the set speed. Running slower will cause something to smoke, either the motor of speed controller.

Yeah, thanks for the info on capacitors as well I knew there was a reason they couldn't be used on some motors but couldn't remember why.

Re: Belt Grinder Build

Thanks for setting me straight. I didn't think about the capacitor start. Never used one anywhere close to rated capacity of 15A.

Re: Belt Grinder Build

Originally Posted by _Dom

Router Speed Control from harbor freight works well for single phase vfd. Used to be available in 220V as well. Their website compared it to something from Rockler. I cannot remember the horsepower rating on mine.

No

A router speed controller is for universal type motors with brushes, like routers and other portable electric tools.
Low HP motors

That motor he will use is 2hp three phase induction motor

Not the same thing and not interchangeable or compatible.

Re: Belt Grinder Build

Originally Posted by _Dom

Router Speed Control from harbor freight works well for single phase vfd. Used to be available in 220V as well. Their website compared it to something from Rockler. I cannot remember the horsepower rating on mine.

I'll disagree with that. I have one and occasionally use it to cut aluminum on my miter saw. It loses power really fast as you turn down the frequency. But, for $15, after the 20% off coupon, it's worth playing with.

I have an ABB 220v 2.2kw , single to 3 phase, VFD on my lathe and that works like a charm.

Dave

Re: Belt Grinder Build

I change my motor out to use a single phase input 120 VAC to 3 phase 220 VAC output, this allows for full speed control. the VFD in the image will allow up to 90 hz to the motor for 1.5 times normal speed, some of the more expensive ones will to 120 Hz or 2 times normal speed. You cannot use a speed control on a capacitor start motor, because they have a speed switch the drops the capacitor after it reaches the set speed. Running slower will cause something to smoke, either the motor of speed controller.

Re: Belt Grinder Build

Router Speed Control from harbor freight works well for single phase vfd. Used to be available in 220V as well. Their website compared it to something from Rockler. I cannot remember the horsepower rating on mine.

Re: Belt Grinder Build

I went with this one.

https://dealerselectric.com/FM50-202-N4.asp

Goes on sale from time to time I believe. I got it for $150.

Its older but its fully enclosed.

Haven't wired it up yet.

Re: Belt Grinder Build

Originally Posted by Tarmstrong

Unless you know some magic to make a single into a variable.

I believe they do make single-phase output VFDs but I don't know enough about them to say for sure they would work with your motor. I am definitely not an expert on motors. I found my motor used on craigslist years ago and think the VFD was only 150 or so on eBay. Just have to get a VFD capable of at least the motors HP.

Re: Belt Grinder Build

Single...so I need a new motor...

Unless you know some magic to make a single into a variable.

Re: Belt Grinder Build

Originally Posted by Tarmstrong

Great build...

Could you give some info on that control fir the motor please...I need to get a motor and Control for speed adjustment for mine...

Attachment 1711568

Your grinder looks good as well. Unfortunately, I took the VFD I have apart years ago when I was using it for another tool and put it in a weatherproof case so I can't find a model number on it. It is a cheapo from eBay the only issue was it had a cooling fan that could suck metal shavings into it. That's why I put it in the case. I attached a pic of the front.

Is your motor single phase or 3 phase?

Attachment 1711569

Re: Belt Grinder Build

Great build...

Could you give some info on that control fir the motor please...I need to get a motor and Control for speed adjustment for mine...

Attachment 1711568

Re: Belt Grinder Build

Originally Posted by Larry4406

Nice build.

Where did your source your drive and driven wheels?

Thanks, https://www.knifegrinderparts.com I think I am going to order the small contact wheels from them as well.

Re: Belt Grinder Build

Nice build.

Where did your source your drive and driven wheels?

Re: Belt Grinder Build

Originally Posted by _Dom

That looks excellent! Thanks for all the pictures, I like the flat face vs radius wheel option. I was puzzling over the tool rest, seeing the vertical and angle adjustment clearly. I just didn't see keeping it centered on the belt. Especially as the belt orientation changes from vertical to horizontal. I like how the geometry maintains center in both positions with either the radius wheel or flat face belt. I think the secret is position of the bottom wheel of the flat face compared to the radius wheel. Appreciate you sharing this build.

Thanks and You're welcome! The belts always track centered on the hinge bolt and as long as the height of the attachment is where it should be it will stay centered.

Re: Belt Grinder Build

That looks excellent! Thanks for all the pictures, I like the flat face vs radius wheel option. I was puzzling over the tool rest, seeing the vertical and angle adjustment clearly. I just didn't see keeping it centered on the belt. Especially as the belt orientation changes from vertical to horizontal. I like how the geometry maintains center in both positions with either the radius wheel or flat face belt. I think the secret is position of the bottom wheel of the flat face compared to the radius wheel. Appreciate you sharing this build.

Re: Belt Grinder Build

Attachment 1711559Attachment 1711560